Process for spinning polyamides which contain a phenylphosphinate and product



United S e ge 01 Claims. 1 (CI. 18-54) This invention relates'to the production of drawn funicularastructureszproduced from a polyamide. More particularly it is Concerned with a process for increasing the draw ratio at constant break elongation of a filament, yarn, thread orthe like produced from a polyamide.

- It is an object of the present invention to producea novel, drawn funicular structure produced from a polyamide.

Another object is to provide a process for increasing the draw ratio at constant break elongation of a filament, yarn, thread'or the like produced from a polyamide.

These and other objects will become apparent in the course of the following specification and claims.

The products of the present invention have obvious utility in conventional textile applications, such as the production of staple, flock, thread, yarn, woven fabric, knitted fabric, batts, fillings and the like.

By a funicular structure is meant a shaped article in filamentous form, such as a filament, thread, yarn, staple, fiock,ribbon and the like.

In accordance with the present invention, the draw ratio at constant break elongation of a funicular structure produced from a polyamide is increased by meltpolymerizing the monomer in the presence of a finely V ROI CWONa wherein. the hexagon represents the benzene nucleus and R is a member of the class consisting of hydrogen, lower alkyl, lower alkoxy and halogen, melt-spinning the polymer containing the said inert material and phosphinate compound to form a funicular structure and thereafter drawing the funicular structure at a draw ratio in excess of 100%,of that obtainable at the same break elongation frornthesame funicularstructure prepared in the absence of the said phenyl phosphinate compound. The increase in draw ratio in this process is then proportional to the, amount of the inert material. The compound whose. structure is represented above will be referred to hereinafter as a phenyl phosphinate compound.

The term, polyamide is used in this invention to signify .a polycarbonamide having recurring amide units as an integral part of the main polymer chain. The terms lower -alky1" and lower alkoxy are used to designate a radical'containing from 1 to 3 carbon atoms. The terminology, drawing the funicular structure phosphinate compound is used to signify that the resulting structure containing the phosphinate compound is drawn to a higher degree (at the same break elongation)'than that obtainable in the absence of this compound. Thus' in the prior art, when a yarn was desired having a particular break elongation, the amount it could be drawn 'was' limited to.a particular value. When the compounds of the present inv'eutionare employed, the

yarn is drawn a greater amount (increasing productivity) Without changingthe desired break elongation. The drawratio of the present invention is thus in excess of of that obtainable at the same break elongation from the same funicular structure prepared in the absence of Example I A stainless steel autoclave equipped with a charging lock as described inUnited StatesP'atent No. 2,278,878, is charged with 467 pounds of an aqueous solution containing 47% by weight hexamethylene diammonium adipate, 5.3 pounds lof an aqueous solution containing 20% by weight of sodium phenyl phosphinate (0.53% based on polymer weight) and 2.1 pounds of an aqueous solution containing 25% by weight acetic acid. The autoclave is purged of air, filled with nitrogen and heated until its temperature reaches approximately 200 C. and 200 pounds per square inch pressure. At this stage bleeding off of water vapor is begun and 0.24 pound of an aqueous slurry containing 20%. by weight of titanium dioxide (0.02% based on polymeric reactants) is added to the reaction mass. The polymerization cycle is continued as taught in Example 1 of United States Patent No. 2,163,636. Upon completion of the reaction the molten polymenhaving a relative viscosity of 37, is extruded in the form of a'ribbon upon a casting wheel. After quenching it is cut into chips suitable for remelting at the grid of a spinning assembly. Such a technique is taught in Example 1 of United States Patent No.

The polyhexamethylene adipamide flake obtained as disclosed above is steam spun in the apparatus disclosed in United States Patent No. 2,571,975. The grid and melt pool temperature is maintained at 290 C. The molten polymer is spun through a 13-hole spinneret, each orifice having a diameter of 0.007 inch. The extruded yarn is collected at a rate of about 1200 yards per minute. It is cold drawn 3.56 times its extruded length in the apparatus disclosed in United States Patent'No. 2,289,232 to produce a yarn having a break elongation of 28:2%. The speed of the pump delivering molten polymer to the spinneret is adjusted to provide a final draw denier of 40.

When sodium p-methoxypenyl phosphinate is substituted for the sodium phenyl phosphinate in the above procedure, substantially the same draw ratio is obtained. I A comparative control, containing no sodium phenyl phosphinate is drawn only 3.36 times its extruded length to the same break elongation. Due to the increase in draw ratio possible when following the teachings of the present invention, a productivity increase of 6% is real- 7 Patented r. s, ss e Example III A batch of polymer is prepared followingthe technique of Example'I but increasing the titanium dioxide content to 2.0% based on the weight of the polymer. A draw ratio of 3.82 is attained upon a fiber produced as taught rnExample I from this polymer whereas a comparative control has a draw ratio of only 3.36 at the same break elongation. An increase in productivity of 13.5% is thereby attained over the prior art methods.

When the process vof the example is modified by adding the same proportion of sodium phenyl phosphinate after polymerization, but before spinning, the fiber formed can be drawn only 3.66 times the extruded length to provixde the same break elongation. Furthermore, only 9% first grade yarn (i.e., free from broken filaments) is produced due to other poor characteristics, as compared to 75% first grade yarn obtained when the phenyl phosphinate compound is added before polymerization.

Example 1 V A batch of polymer is prepared following the technique of Example I, but substituting 0.2% by weight based on polymer of aluminum oxide for the titanium dioxide. A draw ratio of 3.71 is attained upon a fiber produced, as taught in Example I, from this polymer. A comparative control, containing no sodium phenyl phosphinate has a draw ratio of only 3.36 at the same break elongation. The adjuvant increases productivity by 10%.

Example V A batch of polymer is prepared following the technique of Example I but instead of 0.53% sodium phenyl phosphinate is added 0.53% (based on the polymer weight) of sodium p-methylphenyl phosphinate. A draw ratio of 3.61 is obtained upon a fiber produced as taught in Example I from this polymer. A comparative control containing no sodium p-methylphenyl phosphinate has a draw ratio of only 3.36 at the same break elongation. The process of the invention thereby increases productivity by 7%.

When sodium p-chlorophenyl phosphinate is substituted for the sodium p-methylphenyl phosphinate in the above procedure, substantially the same results are obtained.

As is demonstrated in the above examples, it is essential that the phenyl phosphinate compound be present during polymer preparation and the fabricating processes of spinning and drawing. After the funicular structure is formed and drawn the phenyl phosphinate compound may be removed by solvent extraction. Generally water, either cold or warm, is a satisfactory extraction solvent. Soaps or any of the anionic, cationic or nonionic detergents may be employed in the aqueous extracting stream. Other solvents which are nonsolvents for polyamides, such as alcohols, ethers, hydrocarbons and the like may be used.

The use of as little as 0.005% of the phenyl phosphinate compound adjuvant based on the weight of the polymer is observed to improve drawability to some extent. Usually it is preferred to add from about 0.2% to 1% of the phenyl phosphinate. Amounts up to the limit of solubility of the particular phosphinate in a particular. polyamide is frequently advantageous. Most of these compounds are not highly soluble in molten polyamides, and the addition of amounts exceeding the limit of solubility, which is generally about 3%, is usually not desirable. For sodium phenyl phosphinate, thepreferred concentration in polyhexamethylene adipamide is from about 0.25% to about 0.5%. Other suitable phosphinate compounds are the p-ethyl-, p-isopropyl-, p-ethoxy-, p-propoxy-, and p-bromo-, derivatives of sodium phenyl phosphinate.

The solubility of these'compoundsalso depends on the molten polymer.

the polyamide in which they are to be incorporated. For example, the polymer made from episilon-caprolactarn will dissolve about 0.3% sodium phenyl phosphinate.

Any finely divided inert material may be substituted for the titanium dioxide and aluminum oxide of the present invention. Among such materials may be mentioned powdered glass, silicon dioxide, calcium sulfate, barium sulfate, kaolin, clay, zinc oxide, lithopone (barium sulfate and zinc sulfide), talc and other related materials which may be dispersed in their finely divided state in Titanium dioxide is preferred. By the term finely divided, inert materia'l is meant a material which has no chemical action on said-polymer and which is in a state of division of the order of yarn delustering or pigmenting material. The amount of finely divided inert material added will depend on the opacity or degree of pigmentation desired in the final product. The amounts generally used are from about 0.01% to about 10% with amounts of from about 0.02% to about 5% being preferred. The advantages in increased drawability of the spun yarn are greater in proportion as the amount of finely divided inert material is increased. The use of quantities so great that homogeneity cannot be attained or that fiber strength sufiers unduly, must be avoided. V

The drawing operatio'n'is performed onconventional equipment employing either cold drawing (between room temperature and elevated temperatures less than.

truded or shaped articles which may be drawn. If such.

articles are of suificiently thin cross section, the phosphinate compound can be extracted therefrom. The compositions embodying this invention may contain the usual amounts of conventional additives, such as plasticizers and the like.

The invention is broadly applicable to polyamides prepared by melt polymerization. Such materials formed by the reactions of diamines and dicarboxylic acid as well as those formed by polymerization of amino acids are suitable. A valuable class of reactants for use are diamines of formula NH RNH and dicarboxylic acid of formula HOOCR'COOH in which R and R are divalent hydrocarbon radicals free from aliphatic unsaturation and in which each of R and R' has a chain length of at least two carbon atoms. Especially useful reactants within this group are those in which R is (CH and R is (CH in which x is at least 4 and y is at least 3. 'Polyamides derived from reactants of this type yield filaments of ex cellent quality. Instead of using a single diamine and a. single dicarboxylic acid, mixtures of diamines and/or dicarboxylic acids can be employed. In order to obtain a spinnable product the diamines and dicarboxylic acid should be used in substantially equimolecular proportions, that is not more than about 5% excess of either reactant should be employed. A small excess of either reactant may be desirable in order to obtain viscosity stable products.

Many modifications will be apparent to those skilled in the art from a reading of the above without a departure from the inventive concept.

This application is a continuation-in-part ofU.S. applicationSerial No. 514,389, filed June 9 1955.

What is claimed is:

1. A process of preparing a drawn funicular structure prepared from a polyamide which comprises preparing the polymer by melt polymerization in the presence of a finely divided inert material and at least 0.005%, based ROI? 0) ON a wherein the hexagon represents the benzene nucleus and R is a member of the class consisting of hydrogen, lower alkyl, lower alkoxy and halogen, melt-spinning the polymer containing the said inert material and phosphinate compound to form a funicular structure and thereafter drawing the funicular structure at a draw ratio in excess of 100% of that obtainable at the same break elongation from the same funicular structure prepared in the absence of the said phenyl phosphinate compound.

2. The process of claim 1 whereinthe polyamide is poly(hexamethylene adipamide).

3. The process of claim 1 wherein the phosphinate compound is sodium phenyl phosphinate. V

4. The process of claim 1 wherein the finely divided inert material is titanium dioxide.

5. The process of claim 1 wherein the finely divided inert material is aluminum oxide.

6. The product formed by the process of claim 1.

7. The product formed by the process of claim 2.

8. The product formed by the process of claim 3.

9; The product formed by the process of claim 4.

10. The product formed by the process of claim 5.

References Cited in the file of this patent UNITED STATES PATENTS Stamatofi Mar.- 29. 1955 

1. A PROCESS OF PREPARING A DRAWN FUNICULAR STRUCTURE PREPARED FROM A POLYAMIDE WHICH COMPRISES PREPARING THE POLYMER BY MELT POLYMERIZATION IN THE PRESENCE OF A FINELY DIVIDED INERT MATERIAL AND AT LEAST 0.005%, BASED ON THE WEIGHT OF THE POLYMER, OF A PHENYL PHOSPHINATE COMPOUND OF THE FORMULA: 